Electro magnetic scale



April 26, 1960 D. D. O'NEILL ELECTRO MAGNETIC SCALE 2 Sheets-Sheet 1Filed Aug. 30, 1955 R II 0 U T e m /N v u N 1 D m m 0 April 26, 1960 D.D. O'NEILL spscmo mcusnc SCALE 2 Sheets-Sheet 2 Filed Aug. 30, 1955 Fig.3

INVENTOR 70 5+ Supp/y man/s a awe/w United States Patent ELECTROMAGNETIC SCALE Dennis D. ONeill, Hinsdale, N.H.

Application August 30, 1955, Serial No. 531,407

1 Claim. (Cl. 249-47) The present invention relates to improvements inscales.

The present invention relates more particularly to an electro magneticscale possessing novel and unique properties. My invention differs fromany automatic scales known heretofore in that in the prior art scalesthe material to be weighed is balanced in some manner against a. springor a standard weight. Commonly, one pound of material is balancedagainst a one pound weight, though, of course, more or less weight maybe used as a standard, if a lever is employed. a

In prior art arrangements, the beam of necessity undergoes movementduring the weighing cycle. It is my purpose to balance the material tobe weighed, such material commonly known as a draft, against an electromagnet, solenoid, or coil, hereinafter called a weigh or weighingsolenoid. There will be no movement of the scale beam or requiredmovement of the scale beam to accomplish the triggering of the device byusing the characteristics of an overloaded alternating current electromagnet.

It is a further object of the invention to trigger certain controlsunder the influence and control of current which is caused to be drawnin an electro magnet by the load being weighed.

Additional objects of the invention will appear from the followingdescription in which the preferred embodiment of the invention has beenset forth in detail in conjunction with the accompanying drawing.Referring to the drawings:

Figure 1 is a cross section through the automatic electro magnetic scaleaccording to the invention showing the weighing hopper in closedposition;

Fig. 2 is a fragmentary cross sectional view corresponding to Fig. l butshowing the weighing hopper in open position;

Fig. 3 is a fragmentary cross sectional view corresponding to Fig. 1 butshowing the inlet hopper in closed position, rather than in the openposition shown in Fig. 1;

Fig. 4 is a circuit diagram of the controls which bring about thedesired operation according to the invention.

1 have proved by experiment that a solenoid energized by AC. whenrequired to hold an ever increasing load will, after a certain point,cause more current to flow in the circuit supplying such solenoid. Theincreased flow of current is what I am using to trigger the variousmechanisms of the scale, without giving rise to any movement of thescale beam, until after the draft is discharged. As will appearhereinafter moreover, the scale is capable of automatically regulatingitself to the supply of material which advances to the scale.

Referring to the drawings, the scale consists of an inlet hopper 20,comprising walls 21, 21 and having a bottom opening 22. Disposed belowhopper 20 is a weighing hopper 60 having walls 61, 61' and connected toa scale beam 54 at a pivot point 52.. The bottom of hopper 60 is closedby a gate 34. pivoted at 38 and urged into'closed position by anextension or bar 39 having 2,934,304 Patented Apr. 26,1960

thereon an adjustable weight 36. Scale beam 54 is pivoted on aknife-edge pivot 50. A movable weight 56 is provided on beam 54 in orderto counterbalance the Weight of hopper 60. Any weight containedby hopper60 is counterbalanced by a weighing solenoid 62, which is movable alongscale frame 72 by loosening a thumb screw 70. Solenoid 62 has associatedtherewith a loop 76 which is movable with solenoid 62 and through whichloop the beam 54 extends. When the beam 54 is perfectly balanced, aswitch 58 is closed thereby.

It will be observed that weighing hopper 60 is provided with a latch 40for holding closed the gate 34. A switch 42 is located in such aposition with respect to gate 34 that when the latter is closed, theswitch 42 is likewise closed. A solenoid 44 is provided for the purposeof releasing the latch 40 through the intermediary of a link 45connected to the latch by means such as 47 shown.

The opening 22' at the bottom of inlet hopper 20 is closed by inletgates 22 and 23, which are hinged at 106, and which are operated bysolenoids 28 and 30 mounted in any suitable manner on hopper 20. It willbe observed that the solenoids 28 and 30 operate the inlet gates 22 and23 through'the intermediary of toggle mechanism 24, 25, by the pullingin of armature 92 when switches 96 are closed and by the falling outwhen switches 96 are opened.

There is also provided on hopper 20 a speed control bafile 94, hinged at108, and balanced by a weight 110 disposed upon an extension of bafiie94. Switches 96 and 96 are provided which are operated by baffle 94 whensuch switches are engaged by baffle 94. Switches 96 and 96' areresponsible for controlling the speed control gate through solenoid 92,disposed within the hopper 20, by the pulling in of armature 92 whenswitches 96 are closed and the falling out when switches 96 are opened.

In Fig. 4, 100 represents a switch which leads to the hot side of asource of alternating current, one side of which is grounded. Whenswitch 100 is closed, a connection is established from the hot side ofthe alternating current source through a wire'200 to one of the twocontacts of switch 42, the other contact being connected by a wire 202to one of the twocontacts of switch 58, the other contact beingconnected by a wire 204 to one side of solenoid 28, the other sidethereof being connected to ground by means of a lead 206. A wire 208 isconnected to lead 204 to one side of switch 32, the other side thereofbeing connected by means of a wire 210 to a fixed contact 212 of asingle pole, double throw relay 82. The other fixed contact 214 of relay82 is connected by a lead 216 to one side of solenoid 30, the other sideof which is grounded by means of a lead 220. One side of solenoid 44 isconnected to lead 216 by means of a lead 222, and the other side ofsolenoid 44 is connected by means of a lead 224 to ground. An electronictube 80 is provided, which, as illustrated, is a triode having a plateP; a grid G and a cathode K, the plate being connected by means of alead 226 to the operating coil 230. of relay 82, the other end of theoperating coil being connected by means of a lead 232 to a source of B+voltage. B minus leads to the cathode of tube 80. In the grid cathodecircuit of tube 80 there is a potentiometer 78, the movable contact 240of which is connected byv a lead 242 to-the grid, and by a lead 244 toone side of switch 96', the other side of said switch being connected bya lead 246 to an end of potentiometer 78. The junction of potentiometer78 and lead 246 is connected by a wire 248 to one side of a condenser112, the other side of which is connected by a-lead 250 to the upper endone side of weighing solenoid 62, the other side being connected toground. The upper end of resistor 114 is connected by means of a lead260 to lead 200. A lead 262- connects from lead 260 then to the movableelement of relay 82.

By taking into account material in transit at the feed cut off, theswitch 96' causes feed cut off at a lower weight when the gate 90 isfully open so as to allow for the different amount of material intransit when this gate is fully open than when partially closed.

When master switch 100 is closed, it energizes the weighing solenoid 62.It should be kept in mind, of course, that inlet gates 22, 23 arebalanced in such a manner that they are normally closed. Moreover, ifscale beam 54 is balanced, switch 58 will be closed, as will itscontacts 58a. If the discharge gate 34 of hopper 60 is closed, switch 42as well as its contacts 4211 will also be closed. In the foregoingcircumstances, energization of solenoid 28 will take place, therebyopening the inlet gates 22, 23, and thereby closing switch 32. Materialfrom inlet hopper 20 will now flow into the weighing hopper 60,stressing beam 54 imperceptably within the loop 76 but adequately tomove the beam 54 off of the switch 58, thereby opening contacts 58a. Theweight of the material flowing into weighing hopper 60 will be held byweighing solenoid 62 up to a certain point. As more and more currentflows through resistor 114, a greater and greater potential drop willdevelop thereacross, until a point will be reached at which suchpotential drop, applied in the grid circuit of tube 80, throughcondenser 112, will cause more plate current to flow in tube 80energizing relay coil 230. When relay 82 is actuated, this willdisconnect the supply holding solenoid 28 closed, through switch 32 andwill energize solenoid 30, speeding up the closing of inlet gates 22,23, also energizing solenoid 44, latch 40 being pulled away from gate34. The weight of the material in hopper 69 will overcome the weight ofthe counterbalance 36, thereupon discharging the material into thepackaging equipment. The discharging procedure takes the load off ofsolenoid 62, reducing the current flowing to it, thus lowering thecurrent in tube 80 allowing relay 82 to return to its initial position,thereby opening solenoid 3t} and solenoid 44, closing the holdingcircuit to solenoid 28 through switch 32. Weight 36 overcomes the weightof gate 34, swinging it closed, latch 40 thereupon locking it. Thiscloses switch 42, if scale beam 54 is in balance. Switch 58 will close,thus supplying the pull in current for solenoid 28, starting the cycleover again.

The aforementioned operating principles will be readily apparent tothose skilled in the art. In the event that an alternating currentsolenoid such as that 62 disclosed were required to hold an everincreasing load as would occur upon the opening of gates 22, 23 and anadequate supply of material was contained in the supply hopper 20 or theinlet hopper, a certain point would be reached when the load would tearthe armature from the solenoid. This would be considered the maximumability of the solenoid 62. Thus, when the master switch 100 is closedav small steady flow of alternating current through the resistor 114 andsolenoid 62 will flow to ground or to the other side of the alternatingcurrents supply. Any mechanical load such as drawing a draft attached tothe armature of the solenoid 62 will cause no change in current until itexceeds a greater amount of the rated capacity. Beyond that point, thearmature will chatter with very slight vibrating movements, dependingupon the frequency of the current used. However, the solenoid. maintainscontrol of the load, such as the scale beam, up to one hundred percentof, its rated capacity. The load or scale beam absorbs these vibrationsbut does not effect movement thereof. Due to its inertia, the beam isunable to follow the vibrations. At the instant these vibrations startdue to the overload, there will be an increase in current causing anincreased voltage drop across the resistor 114, causing a differentpotential upon the grid of the tube 80, thus firing it or allowing platecurrent to flow. This energizes the relay to 30- thereby triggering thescale with no movement of the beam 54. Triggering of the scale closesthe gates 22, 23, thereby cutting off the supply and opening gate 34 todischarge the load or draft, thereby taking the mechanical load from thesolenoid 62 which automatically decreases the supply current to thesolenoid 62 to its original steady value.

. This decreases the drop across the resistor 114 allowing the gridpotential of tube to return to normal, cutting out the plate current andallowing relay 230 to return to its original position. Thus, thecontacts 212 are closed and in readiness to start the aforementionedcycle again when the gate 34 closes. The aforementioned action could,with proper adjustment, be delayed until a further increase of chatterand solenoid current occurs, such as is done in the slow speed conditionof the scale. There is one movement of the scale beam which could betechnically called the drawing of a draft that permits the balance ofthe weighing hopper to be checked before each and every draft.

When the inlet gates 22, 23 close, there will be suspended in airbetween them and the material in the weighing hopper 60, a. quantity ofmaterial to be accounted for. That is the purpose of adjustment 70, soweighing solenoid 62 can be moved along the scale 72 and beam 54 to anypoint where the pull on solenoid 62 will be such as to make theelectronic control explained above work at such instant that the totalof what is already in hopper 60 plus the suspended equals the correctweight. Thus, if the combination of 62 plus the electronic controls wereset to trigger at two pounds, and it was desired to have each and everydraft equal two pounds, solenoid 62 would have to be set so there wouldbe less distance between it and point 50 than between point 50 and point52.

A scale operating with the inlet gates having two positions opened andclosed, will from time to time run into trouble, outdrawing its supply.Therefore, I have had to add a speed regulator. This takes the form of abaffle 94, mentioned above, having a counterweight which swings 94 outtowards the center of the hopper 20 when there is a small supply ofmaterial in the hopper 20. When hopper 20. is full, it presses on 94pushing it against switches 96, closing it, thereby energizing solenoid92, pulling gate 99 through lever 116 back out of the way for full flowfast speed. It also closes switch 96' shunting out potentiometer 73.

When the supply to the scale is small, the material in 20 drops below94, allowing it to swing out, opening switches 96, 96', cutting thesupply to solenoid 92, allowing gate 90, which is weighted to close orto swing partially closed. Switch 96 is opened, which now closes thetriggering current to fiow to potentiometer '73, which will be adjustedso there will have to be more material in hopper 66 before the scale istriggered. When the speed control gate is in fast flow position,solenoid 62 will be, adjusted by continually weighing drafts until theright place along 54 is. selected. Now, when gate 9!] swings to slowflow position, drafts will be weighed until the correct setting ofpotentiometer 78 is determined. Thereafter, the weights or drafts willbe right, in either position of gate 90.

When gate 98 swings to its closed position, it does not entirely closethe opening of hopper 21. This is shown in the drawing. When the gate 98is in its closed position, it will impede the flow of material fromhopper 21 to hopper 69, thus slowing down the rate of the scale. When itis open, it will allow a larger quantity of material to flow, thusspeeding up the scale. The amount. of material in. hopper 60 determineswhen the electronic trigger operates. Thus, the rate at which thematerial arrives in the hopper 60 will determine the speed of the scale.Gate 90 is controlled by baffie 94 which in turn is controlled by thesupply in the hopper 20. This, in effect, makes the gate 90 a speedcontrol gate responsive to the supply of material in hopper 21. This isnot to be confused with a so-called dribble flow. The scale goes throughits cycle with either fast or slow flow, or a combination of both, whichis controlled by the amount of the load at which chatter begins and fullcapacity of the solenoid.

In operation, the armature in the solenoid 62 when overloaded orrequired to hold the load close to the maximum ability of the solenoid,will vibrate (if a source of alternating current is employed) back andforth. Such movement will be so rapid that the scale beam will be unableto follow it. From a mechanical point of view, the beam has thus beendescribed as stationary. The cause of the vibration of the armature isdue to the seat of the armature in the solenoid due to the overload. Theoverload in this case is a predetermined quantity of material inweighing hopper 60. The armature of an alternating current solenoid willbecome unseated and chatter loudly, causing more current to flow in thecoil. When a large proportion of the total amount of pressure or weightnecessary to tear the armature from the solenoid is applied, theelectronic trigger shunted across the solenoid coil or the resistor inseries with the solenoid will, if proper adjustments are included in theelectronic trigger, trigger at any point between eighty percent and onehundred percent.

While this specification sets forth a detailed present and preferredconstruction of the invention, nevertheless in practice such deviationsfrom such detail may be resorted to as do not form a departure from thespirit of the invention as defined by the appended claim.

What is claimed is:

An automatic weigher comprising, in combination, an inlet hopper, aninlet gate for selectively opening and closing said inlet hopper, atoggle mechanism for moving said inlet gate to opened and closedpositions, a plurality of solenoids, a first of said solenoids beingoperable to move said toggle mechanism and inlet gate to openedposition, a second of said solenoids being oper- 6 able to move saidtoggle mechanism and inlet gate to closed position, hopper level meansin said inlet hopper responsive to level of material therein, said meansbeing operable to vary the rate of material flow from said inlet hopperin response to various levels of ma terial therein, a weighing scalebeam, a weighing hopper mounted on one end of said scale beam, aweighing solenoid, the core thereof being operably attached to the otherend of said scale beam and operable to hold said beam substantiallymotionless under increasing load in said weighing hopper, a circuitconnected to said weighing solenoid and operable in response to apredetermined level of current in said weighing solenoid due to increaseof load in said weighing hopper to a desired value to cause said secondsolenoid to close said inlet gate, an outlet gate on said weighinghopper, means to open said outlet gate at the same time as said inletgate is closed, means to close said outlet gate upon discharge of theweighing hopper load therethrough, means responsive to the closing ofsaid outlet gate to cause said first solenoid to open said inlet gate,and means responsive to said hopper level means for adjusting the levelof current in said circuit at which said second solenoid is operated,whereby change in feed rate and consequent variation in material intransit between the two hoppers is allowed for in cutting off feed tothe weighing hopper.

References Cited in the file of this patent UNITED STATES PATENTS1,923,745 Platzer Aug. 22, 1933 2,008,305 Johnson July 16, 19352,022,659 Fisher et a1. Dec. 3, 1935 2,081,367 Nicolson May 25, 19372,231,035 Stevens Feb. 11, 1941 2,260,718 Merrifield Oct. 28, 19412,314,654 Merrifield Mar. 23, 1943 2,371,040 Fisher et a1. Mar. 6, 19452,451,891 Vagim Oct. 19, 1948 2,597,831 Willis May 20, 1952 2,602,660Shannon July 8, 1952 2,624,443 Voller Jan. 6, 1953 2,714,472 RichardsonAug. 2, 1955

